Infrared radiation detectors have long been used for producing thermal images which makes it possible to observe scenes at night or through clouds, smoke and dust. A conventional infrared detector is a large scale device, that is, each detector element is much larger than the wavelength of the incident radiation. Such conventional detector elements are purposely designed to be relatively large in order to insure that there is an adequate collection area for the incident radiation. Further, such detectors are made relatively thick to absorb penetrating incident radiation.
A principal limitation in the use of conventional infrared detectors has been the requirement that the detectors be enclosed within a cold chamber. The cooling is required to raise the detectivity of the detector to a usable level. Such cooling is typically provided by the evaporation of liquid gases, such as nitrogen. However, the storage, piping and handling of coolants such as liquid nitrogen is a difficult, expensive and time consuming task. Conventional large area detectors further have relatively low detectivity which reduces the sensitivity of the detector system.
In view of the need for thermal imaging and the difficulties associated with the use of such infrared detectors, such as cooling and low detectivity, there exist a need for an infrared detector which has a much higher detectivity and, as a result, can produce a useful signal at ambient temperature thereby eliminating or reducing the need for cooling equipment.